The present invention relates to a lamp assembly for a substrate processing chamber.
A substrate processing chamber is used to process a substrate such as a semiconductor wafer or display. These chambers often use lamp assemblies, which comprise lamp elements and surrounding structure, to heat the substrate or chamber surfaces. The lamp assemblies emit radiation that can be used to heat and anneal a layer of material on the substrate, as for example in a rapid thermal processing chamber, or to decompose a gas to form a layer on a substrate, as in a CVD or epitaxial growth chamber. The lamp assemblies can rapidly generate infrared heat and are easily controllable, and thus useful, for rapidly heating a substrate.
The lamp assemblies are typically arranged as a patterned array in the chamber to uniformly heat the substrate or chamber surface. An electrical circuit provides power and signals to each lamp assembly. Typically, the lamp assembly is mounted in a receptacle, wire harness, circuit board, or other structure in the chamber. However, arrays of conventional lamp assemblies are often difficult to mount or align in a chamber during its assembly or replacement of the lamps, for example, due to difficulty in accessing the lamp assemblies. Manufacturing tolerances can also generate small dimensional variations within the lamp receptacle or in the space between a plurality of receptacles. Such dimensional variations can make mounting and alignment of a plurality of lamp assemblies into corresponding receptacles difficult and time consuming.
Other problems arise from the flexible connectors and plugs used in the lamp assemblies. For example, one conventional lamp assembly, as disclosed in U.S. Pat. No. 6,350,964 to Boas et al., assigned to Applied Materials, Inc., which is herein incorporated by reference in its entirety, comprises a lamp body, bulb and base. The lamp base mates to a receptacle on a printed circuit board (PCB) structure, facilitating easy removal and replacement of the lamp assemblies. The lamp base has a flexible elastomer plug to facilitate alignment of the lamp assemblies to receptacles on the PCB. The flexible elastomer plug also absorbs thermal expansion stresses that arise when the lamp attains elevated temperatures. However, exposure of this type of elastomer material to excessively high temperatures may lead to loss of flexibility of the elastomer material or thermal degradation of its insulating properties. This may also be a problem when the lamp assembly is exposed to high temperatures during its manufacture. For example, lamp assemblies often include some type of potting compound that is baked at high temperatures to remove or reduce its water content. The water content is removed because it undesirably absorbs the infrared heat energy released by the lamp assembly, reducing the heating efficiency of the lamp assembly. Thus, the flexible elastomer lamp plug does not allow heating to a temperature sufficiently high to limit the removal or reduction of the water content in the potting compound, thereby limiting the efficiency of the lamp assembly.
Thus, it is desirable to have a lamp assembly that can be more easily aligned with mating receptacles in a substrate processing chamber. It is also desirable to have a lamp assembly that is capable of withstanding thermal expansion stresses that arise during substrate processing. It is further desirable for the lamp assembly to have reduced water content. It is further desirable for the lamp assembly to be easily mountable and replaceable in the field.